The present invention relates to a process and an apparatus for cooling a stream of compressed air.
It is frequently desirable to cool a stream of compressed air to remove the heat of compression and, in some cases, to cool the air to a subambient temperature, such as in the case where an adiabatic compressor is used to compress air to be separated in a cryogenic distillation plant.
The standard procedure is to send the compressed air to a cooling tower where it is cooled by direct contact with water from a refrigeration circuit. U.S. Pat. Nos. 4,367,082, and 5,669,237 describe standard cryogenic distillation air separation units in which air is cooled by indirect heat exchange with water and then purified and sent to the columns to be separated.
It is known from U.S. Pat. No. 4,461,154 that air compressed in an adiabatic compressor may be used to preheat boiler feed water. U.S. Pat. No. 6,117,916 describes the use of heat from an adiabatic compressor to warm a working fluid before sending the air from the compressor. The air is then further cooled and sent to an air separation unit.